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Distortion caused by compressor pedal

L

lagerratrobe

Oct 7, 2012
10
0
Seattle
#1
Hi All,

New member of TB as of today. I have a question regarding the effect of a compressor pedal. I just bought a Moen Uni-Comp a week ago and am generally loving it. However, I'm noticing that when I turn the compression up past a very low point, my amp starts to clip when I play low notes ( open E string, or any of the first 7 frets on that string). The clipping seems to go away when I play higher notes. I'm curious if this could be because I'm playing through some old guitar amps, with speakers that are not optimized for bass, or whether this is simply a side-effect of using a compressor that will exist with any amp?

I have an old Gibson Skylark (5 watt) that I practice on at home, and an Ampeg VT22 that I use elsewehere. Both amps clip in the same way when the compressor is used. At the moment I'm not interested in replacing them, but I would definitely consider replacing the speakers, if that would help.

Thanks.
 
#2
This may be due to the attack/release settings on the compressor. Because low frequencies are so long a fast release time may cause the compressor to ride the wave, flicking on and off very quickly which sounds like distortion. (I hope I got the explanation right! Anyway, I am sure Bongomania will be by to explain this better.) What I recommend is set the release time to about 1/2 second, (500 milliseconds). That should help.
 
#3
Thanks, that's useful to know. Unfortunately, the Uni-Comp doesn't have a setting to alter release time. It does have a "Bias" knob that acts like a band pass EQ (according to the ovnilab website). I currently have it set to trim out high freqs, so about 1/2 way into the "Low" region. Maybe I'm boosting the low freqs too much?
 
#5
scottfeldstein said:
Maybe the signal out of the compressor is too hot. Does it have a level? Something to adjust the gain to compensate for any level loss by the compression? Perhaps it's too high. Just a shot in the dark.
Click to expand...

this makes good sense. does you amp have a pad?

Edit: I re-read the part about you using guitar amps for bass, were they bass'y before you added the comp? Yea, like Bongo said, roll off the low eq for sure.
 
#6
Yes, I do have a Gain knob on the pedal. But it seems that if I leave the "Compression" setting dialed up past say 20%, I can reduce to Gain to where I almost have no sound - and it still causes the speaker to make a disgusted sound. Maybe it's not actually tube distortion, but the speaker reacting strangely to the compressed low ferquencies?
 
#7
Low frequencies generally need to have much taller amplitude peaks in order to sound "as loud as" higher frequencies. And just plucking various notes with equal finger strength, the fat low strings will tend to have taller amplitude peaks anyway. When you add single-band compression (like the Moen and most other pedals), the taller low-note peaks trigger the compression and this ducks down all frequencies at the same time. Net result, with the EQ tilted to the bass side, is a HUGE concentration of energy in the low frequency range, even when it doesn't sound like the lows are all that loud.

Then you play through amps that are designed to not handle much low end, and of course they distort.

In order to use those amps and get decent tone with less distortion, you'll actually need to tilt the EQ to the high side, cutting some lows.
 
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#8
Very True.. +1

BFunk said:
This may be due to the attack/release settings on the compressor. Because low frequencies are so long a fast release time may cause the compressor to ride the wave, flicking on and off very quickly which sounds like distortion. (I hope I got the explanation right! Anyway, I am sure Bongomania will be by to explain this better.) What I recommend is set the release time to about 1/2 second, (500 milliseconds). That should help.
Click to expand...
 
#9
had a same problem with a Keeley clone. I'm using a SUB Ray4 which had active pickups, no matter how low I set the gain on the bass, it will always result in a bit of overdriven signal. I thought it was the hot signal from the bass that caused the distorted result
 
#10
Lol at "Keeley clone" (the Keeley is a clone).

Anyway yes it is also possible to cause the pedal itself to distort, given a high-output instrument. But everything else the OP described in his case suggested the amp and its speakers distorting, with help from the compressor.
 
#11
bongomania said:
Lol at "Keeley clone" (the Keeley is a clone).

Anyway yes it is also possible to cause the pedal itself to distort, given a high-output instrument. But everything else the OP described in his case suggested the amp and its speakers distorting, with help from the compressor.
Click to expand...

LOL, so it was a clone of a clone... cloneception! :D

I couldn't find any info on what the bass is being used in the OP, so hopefully this can be added to the list of possible solutions

since the problem emerges at both guitar amps, I would suggest to start with all EQ knobs dead left, and turn it up gradually to see if there's any signal breakups along the way.
 
#12
Hey, appreciate all the helpful advice from people, but I think I found the problem. I got home prepared to crank the bias knob to the right, and to experiment with lowering the pickups, but then I realized that the little red light on the pedal was kinda dim. I found a new battery, got everything fired up and then could not get the problem to repeat, no matter how had I tried. Even pushing hard and as loud as I could, the amp simply broke up in the nice tubey way that we all know and love. None of that harsh "gack" of a breakup. Sounds simply beautiful now.

I dunno what happens to the signal when the battery in the compressor is going dead, but it sure seems like that might have been the culprit. I've unplugged the pedal completely now when I'm not playing.

Oh, and for the people who asked, it's a Saga kit bass, so I have no idea what sort of pickups it has. I think they are the plain-jane split single coils that are traditional in a P-Bass. I have a set of DiMarzio's that I intended to put in, but the stock ones sound good enough that I haven't been inspired to make the swap.

Thanks again.
--
 
#15
That may be because most of us aren't running on batteries. But now that he mentions it, that's the reason I stopped using batteries, ill effects.

I just got a MXR MC403 power station and has 2 variable outputs, so you can have them set to unusual voltages and something else they mention was simulating the dying battery effect. Apparently this is desired for certain distortion/OD pedals. Always learning.
 

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